No. 576] VARIATION IN DROSOPHILA 



735 



The crosses with Purple-eyed flies presented no diffi- 

 culties but ran smoothly aside from the fact that the 

 purple-eyed flies had Curved wings, and as remarked 

 above, Curved wings sometimes get bedraggled. 



TABLE XVIII 



Back-crosses of F, Females of the Cross Beaded <J X Black J ro 

 Black Males of Normal Stock 



(d) Linkage to Third Chromosome Genes 

 We have said tentatively that there was perhaps a non- 

 sex-linked lethal gene for Beaded wings in the second 

 chromosome, and that possibly the cytoplasm carried by 

 the egg disposes males toward or away from Beadedness 

 according to whether the fly that bore the egg was or was 

 not Beaded. These relations are not securely deter- 

 mined, and the data arc still incomplete. The relation of 

 Beaded wings to characters whose genes are in the third 

 chromosome is much clearer. All crosses that bear on 

 this problem point to one fact, namely, that there is a 

 gene for the production of Beaded wings in the third 

 chromosome, and that this gene is very closely linked to 

 Ebony, and very loosely linked to Pink. Tests have been 

 made between Beaded and the third chromosome char- 

 acters, Maroon, Sepia, and Pink eyes and Ebony body 

 color. 



TABLE XIX 



F 2 Counts of the Cross Pink Beaded J X Black $ 



